Backup discs no longer work

I have soft modded my wii and have played many of the back up discs I have, but after not sing it for a while I find I'm getting DVD timeouts in neogamma with discs that use to work. I've opened the wii up and cleaned the laser, and my original games seem to work fine. But all my backup disc fail with timeout or DVD error. I've tried neogamma r6 and r9 and cios rev 20 and cios rev 17 in slot 249. What can I do now?